Liquid-liquid equilibria of systems containing 2-methoxyphenol or 2-ethoxyphenol and n-alkanes

TL;DR

This study maps liquid-liquid phase diagrams for systems of 2-methoxyphenol or 2-ethoxyphenol with various n-alkanes, revealing an upper critical solution temperature that increases with alkane size and depends on molecular interactions.

Contribution

It provides new experimental phase diagrams for these phenol-alkane systems using laser scattering, highlighting how molecular structure influences phase behavior.

Findings

All mixtures exhibit an upper critical solution temperature.

The critical temperature increases with alkane chain length.

Dipolar interactions vary with phenol derivatives, affecting phase separation.

Abstract

Liquid-liquid equilibria phase diagrams have been determined for the systems: 2-methoxyphenol + n-decane, or + n-dodecane, or + n-tetradecane or + n-hexadecane and for 2-ethoxyphenol + n-octane, or + n-dodecane, or + n-tetradecane, or + n-hexadecane. The experimental method used is based on the observation, by means of a laser scattering technique, of the turbidity produced on cooling when a second phase appears. All the mixtures studied show an upper critical solution temperature, which increases with the n-alkane size. Dipolar interactions between like molecules become stronger in the sequence: 2-ethoxyphenol < 2-methoxyphenol < phenol. Data available in the literature suggest that this relative variation is also valid for n-alkane mixtures containing other substituted anilines, characterized by having a second polar group. The dependence of the upper critical solution temperature on the molecular structure of the polar aromatic compound involved is shortly discussed in terms of intramolecular and steric effects.